Mini-Strokes?

My 89 yr. old mother was hospitalized this week due to what the doctor thought was a mini-stroke, but all tests have come back negative--CT scan, carotid artery echocardiogram, MRI. She had suddenly become extremely weak, emotional, confused, and her short-term memory is not good. She had headaches 2 wks. prior to her hospitalization, and one particular morning, she was very hard to wake up. The doctor now just says that since all tests were neg., her problems are due to her age, and that nothing can be done. He did send her for physical therapy so she will regain enough strength to walk again. She is now in a nursing home for at least 2 wks. In spite of the tests, I believe she had a stroke. Her face droops a little on one side & she complains of a funny feeling that comes & goes inside her head that causes her problems when walking--she feels like she's going to fall over. I'd like to talk with anyone who may have had a similar experience. Thanks!